Means for interrupting the movement of a tool



Feb. 18, 1947. w, JOHNDREW 2,416,055

MEANS FOR INTERRUPTING THE MOVEMENT OF A TOOL Filed Nv. 13, 1943 2 Sheets-Sheet 1 -2 1 ,0, T /a& M6

lNVENTOR Wilbur dohndre ATTORNEYS Patented Feb. 18, 1947 UNITED STATES RATENT OFFICE MEANS FOR INTERRUPTING THE MOVE- MENT OF A TOOL 6 Claims. l

My invention relates in general to means for interrupting the movement of a tool, and more particularly to such means which are actuated by contact with the workpiece being acted upon for the performance of useful work by the tool itself and/or to initiate the operation of some cooperating tool in sequential manner. While the invention is applicable to any form of machine where it is desired to move a tool toward and into contact with a workpiece and to stop 2-:

the movement of the tool by such contact, I have shown and described the invention in connection with the bucking tool of a riveting machine.

This application is a division of my previously filed application Serial No. 452,606, upon automatic multiple riveters,

The principal object of my invention has been to provide means controlled by the contact of the tool with the workpiece which shall stop further movement of the tool.

Another object has been to provide a tripping plate carried at and forming at least a part of the working surface of the tool for stopping the movement of the tool upon contact with the surface of a workpiece, whereby an operator may move the tool toward the workpiece from any distance with the assurance that the movement of the tool will be stopped at a predetermined position in its travel.

The above objects and advantages have been accomplished by the device shown in the accompanying drawings, of which:

Fig. 1 is a fragmentary front view showing a riveting machine equipped with my invention.

Fig. 2 is a longitudinal section view of the bucking tool of the riveting machine.

Fig. 3 is a bottom view of the bucking ram feed screw showing its means of attachment to the drive shaft thereof.

Fig. 4 is a diagrammatic view of one form of electric control circuit used in connection with my invention.

When my invention is to be used in connection with a riveting machine ID as shown in Fig. 1, it is preferably applied to the bucking unit H thereof. For illustrative purposes the riveting unit ll of the riveting machine is also shown, although my invention does not contemplate or is it necessary to have a riveting or other coacting tool in addition to the bucking unit which carries my invention. When used in connection with a riveting machine such as shown in Fig. 1, the bucking unit H is movable laterally across the opening l3 of the machine upon ways l4. Z

Engaging with the ways I4 is a base plate i5 which carries the bucking unit.

So as to make it convenient and easy to adjust the bucking unit, it is mounted upon supporting rollers 16 which are engageable with supporting rails 20 carried by the ways l4 and in spaced relation therewith. The rollers iii are carried upon eccentric sleeves 2| which make it possible to adjust the roller so that there is only a slight clearance between the top bearing face of the base plate 15 and the ways 14. Obviously, this clearance space does not exist when the bucking unit is operating since pressure upon the unit will cause it to bear firmly against the ways hi. Guide rollers 22 are likewise carried by the base plate and engage with the inner surfaces of the ways Id, thereby guiding the unit across the ways.

The bucking unit comprises a cylinder 23 having a base flange 24 which is secured to the base plate 15 of the unit. The cylinder is provided with a longitudinal bore 2'! in which is slidably mounted a bucking ram 25. This ram is reciprocated within the cylinder preferably by means of a ram screw 26. This screw is mounted within a longitudinal bore 3!) formed in the ram, and passes through a nut 31, secured to the upper end of the ram. This screw is preferably mounted upon a drive shaft 32 which extends longitudinally through the screw. The shaft is secured to the screw in non-rotatable manner preferably by means of a diametrically arranged key 33 which engages a diametrical slot 34 formed in the screw and also with a registering diametrical slot 35 formed in the lower end of the shaft 32. The upper end of the drive shaft is mounted in the basefiange 24 of the unit in an anti-friction bearing 36. An operating motor 31 of the reversing type is mounted upon the base plate It and its shaft 46 is connected to the drive shaft 32 by any suitable means. So as to prevent the ram 25 from rotating within the cylinder 23, I provide a key 4| carried preferably by the cylinder and engageable with a key way 32 formed in the ram.

The bucking tool or anvil 43 of the riveting machine is carried at the lower end of the ram 25 and is preferably secured to an index plate 44. This index plate is secured in rotatable manner to the bottom surface of the ram preferably by means of an index flange 55, suitable detent means 46 being employed to hold the index plate in its adjusted position. v

As shown in Fig. 2. my invention comprises a tripping plate 50 arranged in spaced relation with the bottom abutment face of the bucking 162, and Hit. 10 N35 and H95 which receive their electrical tool and forming the work surface of such tool. This plate is mounted upon a plate rod which extends through an aperture 52 formed in the bucking tool. A flange 53 is preferably carried at the upper end of the rod 5| to prevent the rod and plate from becoming displaced. The flange 53 is mounted in an enlarged recess 55 and a helical spring 55 is mounted within this recess, having one end bearing against the flange 53 and the other end preferably against the bottom surface of the ram 25, whereby the tripping plate will be maintained normally in the position shown in Fig. 2. In order to keep the tripping plate in alignment with the bucking tool or anvil, I 'may use one or more pins 56 which are carried by the tripping plate and engaged with registering apertures 653 formed in the bucking tool or anvil.

The bore 38 in the ram 25 is preferably considerably longer than the screw 25%, and in the space thereby provided I mount a control switch 5!. This switch is secured to the bucking ram for movement therewith and the button 62 thereof is in contact with a switch rod 63. This rod is slidably mounted within aperture formed 1..

centrally through the bottom portion of the ram and has its lower end contacting th flange 53 of the plate rod 52, whereby movement of the plate rod through movement of the plate will be conducted to the button 62 of the switch.

Arranged along the side of the ram cylinder is a ram housing 55, and the electric conduit 55 extending from the switch 68 passes through an aperture iii formed in the wall of the ram and upwardly within the housing to the sheaves l2 and Y3 over which it passes to the associated electric controls.

Also mounted within the housing E55 is a switch block M. which is secured to the ram and which carries safety switches '55 and it. The switch l5 engages a spring pressed stop pin 3%] carried by the housing to limit the upward movement of the ram, and the switch 16 engages a spring pressed stop pin 8i carried by the housing and serves to interrupt the current to the motor ii! to stop the ram at the limit of its stroke in the event that the control switch Si or other suitable means for controlling the movement of the ram fail to function.

As will be obvious from the foregoing, as the ram 25 is moved downwardly, it will carry the tripping plate 59 toward the workpiece, and upon contact with such workpiece the tripping plate will be pushed upwardly toward the abutment surface of the bucking tool or anvil 4 3. Such movement will cause the upward movement of the plate rod 55 and switch rod 63, causing the button 52 of the control switch 6! to be depressed. This control switch may be either a normally closed switch or a normally open switch, depending upon the kind of circuit with which it is used. In Fig. 4, I have shown an illustrative circuit in which my invention may be used, and have shown a normally closed control switch. In this circuit two magnetically held contactors 9i] and 9! are employed, the contactor 90 controlling the upward movement of the bucking ram, and the contactor 9i controlling the downward movement. The contactor so is provided with a holding or operating coil 92 and normally open contacts $3, 9 3 and In like manner the contactor ti is provided with a holding or operating coil 5% and normally open contacts it, The power lines are indicated at circuit through the holding coil 58! energy from a suitable source of supply. One side of each of the holding coils S2 and Hill is preferably connected to the power line 5%, current returning to the power line m l through a double throw hand operated switch No. This hand switch has a contact it! which is connected to coil 92 of contactor E53 and a contact H2 which is connected to coil Hi3 of contactor 95. A switch arm H3 serves to connect either contact H! or contactor H2 with the power line let. The control switch 6! is preferably conaected in series with the coil E09, and the safety switch it is also connected in series with the coil and with the control switch iii. The safety switch '55 is connected in series with the coil 92. Contacts 93, 9t and 95 are connected respectively to the motor terminals H4, H5 and 5 iii. In like manner contacts lei, M32 and m3 of contactor 9| are connected respectively to terminals H5, H5 and lid of the motor.

rom the foregoing, it will be clear that when the switch arm MS of switch lid is moved to close the circuit through H2 thereof current will flow from lead H34 through switch El, switch 15, and holding coil llll of contactor Bl back to power line Hit, thereby energizing this operating or holding coil. This will serve to close the normally open contacts iti, Hi2 and 963 of this contactor and supply current to motor 37 to cause it to move the ram downwardly. When the "bucking ram has reached the point in its travel where the tripping plate 59 contacts the workpiece, the control switch Si will be opened thereby interrupting the liow of current through the holding or operating coil ms and allowing contacts lfii, 62, and 553 to fall to their normal open positions, thereby interrupting current to the motor and stopping further downward travel of the bucking ram. Obviously, should, for any reason, the control switch 6! fail to open, further downward movement of the ram would cause safety switch it to be opened by contact with the spring pressed pin 88, thereby breaking the When it is desired to move the ram upwardly, the arm H3 of the switch MB is moved so as to close the circuit through the contact ill thereof. Current will now flow from the power line m4 through safety switch it and holding or operating coil 92 of the contactor 93. Energization of this coil will cause the closing of the normally open contacts 93, '94 and 95 of the contactor, thereby allowing current to flow from these contacts respectively to the terminals lid H5 and N6 of the motor, whereby the motor is operated in the reverse direction to elevate the ram. When the ram has reached the upper end 'of its predetermined travel, the safety switch 15 will contact the spring pressed stop pin t thereby opening this switch and interrupting the flowof current through the holding coil 92, thereby allowing the contacts 93, 9 and 95 to fall to their normally open positions. Current is thus interruptecl to the motor and the upward travel of the ram is stopped.

Having described my invention, what I claim is:

1, Means for interrupting the movement of a tool, comprising a reciprocating member, power actuated means for reciprocating said member, a tool carried by said member and having an abutment surface movable toward a workpiece, said tool having an axially movable work-engaging part, said part being interposed between said surface and the workpiece and forming the Work-engaging face of said tool, whereby said part will be moved relatively to said surface by and during contact thereof with the workpiece, and means controlled by such relative movement to arrest said reciprocating member at a predetermined place in the working stroke of the tool.

2. Means for interrupting the movement of a tool, comprising a reciprocating member, screw means for reciprocating said member, an electric motor for actuating said screw means, a tool carried by said member and having an abutment surface movable toward a workpiece, said tool having an axially movable work-engaging part, said part being interposed between said surface and the workpiece and forming the work-engaging face of said tool, whereby said part will be moved relatively to said surface by and during contact thereof with the workpiece, switch means carried by and movable with said member for controlling the operation of said motor, and means connecting said tool part with said switch means and operable by and during the relative movement of said tool and said part to interrupt said motor.

3. Means for interrupting the movement of a tool, comprising a reciprocating member, screw means for reciprocating said member, an electric motor for actuating said screw means, a tool carried by said member and having an abutment surface movable toward a workpiece, said tool having an axially movable work-engaging part, said part being interposed between said surface and the workpiece and forming the work-engaging face of said tool, whereby said part will be moved relatively to said surface by and during contact thereof with the workpiece, switch means carried by and movable with said member, a, sprin pressed switch rod slidably mounted in said member and operably connecting said switch with said tool part, whereby said switch will be operated by and during the relative axial movement between said tool and said part to interrupt the movement of said member at a predetermined place in the working stroke of the tool.

4. Means for interrupting the movement of a tool, comprising a reciprocating member, screw means for reciprocating said member, an electric motor for actuating said screw means, a tool can said control switch and said safety switch being connected in series with each other and with said motor, means connecting said control switch with said tool to operate the same by and during the relative axial movement between said tool and said part, and stop means engageable with said safety switch to interrupt 1e current through said motor.

5. Means for interrupting the movement of a tool, comprising a reciprocating member, power actuated means for reciprocating said member, a tool carried by said member and having an abutment surface movable toward the workpiece, said tool having an axially movable work-engaging part substantially coextensive with said surface, said part being interposed between said surface and the workpiece and forming the work-engaging face of the tool, whereby said part will be moved relatively to said surface by and during contact thereof with th workpiece, and means controlled by said relative movement to arrest said reciprocating means at a predetermined place in the working stroke of the tool.

6. Means for interrupting the movement of a tool, comprising a reciprocating member, power actuated means for reciprocating said member, a tool carried by said member and having an abutment surface movable toward the workpiece, a tripping plate carried by said tool and arranged adjacent the abutment surface thereof, said plate being interposed between said surfac and the workpiece and movable relatively to said surface, and means for normally keeping said plate in spaced relation with said surface, whereby upon contact with the workpiece, the plate will move toward said surface and cause the movement of said reciprocating means to be arrested at a predetermined place in the working stroke of the tool.

WILBUR JOHNDREW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,143,716 Scaife Jan. 19, 1939 2,339,597 Barnes Jan. 18, 1944 2,297,596 Westin Sept. 29, 1942 2,328,919 Merriman Sept. 7, 1943 2,134,933 Smith Nov. 1, 1938 316,541 Douglas Mar. 27, 19% 979,617 Weatherson Dec, 27, 1910 2,148,704 Merritt Feb. 28, 1939 2,365,147 Speller Dec. 12, 1944 376,541 Mergenthaler Jan. 17, 1888 

